Helmet



FIG. 1 is a front, top and right side perspective view of a helmet showing my new design;

FIG. 2 is a front view thereof;

FIG. 3 is a rear view thereof;

FIG. 4 is a top plan view thereof;

FIG. 5 is a bottom plan view thereof; and,

FIG. 6 is a right side view thereof, the left side view being a mirror image of FIG. 6.

The broken lines illustrate portions of the helmet that form no part of the claimed design. The shield of the helmet is transparent. 

CLAIM The ornamental design for a helmet, as shown and described. 